In a common lead-acid storage battery, generally, anode is made of lead dioxide and cathode is made of lead, and the battery electrolyte is a sulfuric acid electrolyte. When connected with an external load, the battery will discharge to generate an electrical current; the reactions on electrodes are as follows: EQU Anode: PbO.sub.2 +SO.sub.4.sup.2 31 4H.sup.+ 2e.fwdarw.PbO.sub.4 +2H.sub.2 O EQU Cathode: Pb+SO.sub.4.sup.2.fwdarw.PbSO.sub.4 +2e
Thus, lead dioxide on the anode is converted to lead sulfate, and lead on the cathode is also converted to lead sulfate. Once lead sulfate is formed, it will adliere to electrodes because of its extreme insolubility. The total chemical reaction of the discharging process is: EQU Pb+2H.sub.2 SO.sub.4 +PbO.sub.2.fwdarw.2PbSO.sub.4 +2H.sub.2 O
The voltage of a single cell of the battery is 2.04V. During discharging, the amount of sulfuric acid in the battery electrolyte decreases, and the amount of water increases.
When connected with an external power source, the battery is charged, the electric current passes through the battery backward, the reactions on the two electrodes are carried out just in a reverse direction to that when discharging, lead and lead dioxide are formed by the reaction of lead sulfate on the anode and cathode respectively, and adhere to their respective electrodes, and water is absorbed. The battery comes back to its initial state. The chemical reaction is taken place as follows: EQU 2PbSO.sub.4 +2H.sub.2 O.fwdarw.Pb+2H.sub.2 SO.sub.4 +PbO.sub.2
The water is electrolyzed simultaneously while the battery is charged, as a result, the water is electrolyzed to hydrogen and oxygen which are then released. The following reactions are taken place: EQU Anode: 4OH.sup.-.fwdarw.2H.sub.2 O+O.sub.2 +4e EQU Cathode: 2H.sup.+ +2e.fwdarw.H.sub.2
The extent of such reactions depends upon the conditions of charging. The reactions would be enhanced when charging is about to complete.
Thus, water must be added frequently during the electrolyzing process in order to make up for the consumption of water, and charging must proceed with caution to prevent hydrogen released in battery from burning and explosion in the air.
At present, the colloidal electrolyte in a lead-acid storage battery is generally prepared by mixing a sodium silicate solution with a sulfuric acid solution. This electrolyte is convenient for use, maintenance, storage and transport, as it is in a colloid state and hardly flows. In addition, the colloidal electrolyte can protect the active subatance from stripping away from electrodes, thus the service life of the battery can be prolonged for more than 20%. However, the internal resistance of a colloidal electrolyte is higher than that of a sulfuric acid electrolyte, thus, the internal resistance of this storage battery is increased and the capacity is reduced.
Swiss Patent No.391807 discloses a lead-acid storage battery with thixtropic colloidal electrolyte. Chinese Patent Application under publication No. 1056019 also discloses a high-capacity colloidal electrolyte and a method for producing the same. Though the colloidal electrolyte and the lead-acid storage battery having a colloidal electrolyte can reduce solution evaporation, percolation and corrosion, to the technical problems in lead-acid storage battery have not been solved completely, and the capacity has not been increased.